Safety and efficacy of topically applied 0.5% and 1% pirfenidone in a canine model of subconjunctival fibrosis.

OBJECTIVE: To evaluate tissue levels, safety, and efficacy of topical ophthalmic 0.5% and 1% pirfenidone in decreasing subconjunctival fibrosis. ANIMAL STUDIED: Twelve normal beagle dogs PROCEDURES: A 5 × 1 mm diameter silicone disk was implanted subconjunctivally in one eye, and then dogs were treated with topical 0.5% pirfenidone (n = 9) in artificial tears or artificial tears alone (n = 3) for 28 days. To evaluate tissue drug levels, a single sample of tears, conjunctiva, and aqueous humor was collected 30 (n = 3), 90 (n = 3), and 180 min (n = 3) following administration of the last drop of pirfenidone, respectively. Fibrous capsule thickness and staining for Ki67 and fibroblast activation protein alpha (FAPα) were evaluated histologically. After a 2-week washout, the experiment was repeated in the opposite eye and using 1% pirfenidone. RESULTS: Treatment with pirfenidone resulted in thinner fibrous capsules and decreased staining for FAPα with no adverse effects. The implant in one dog treated with pirfenidone extruded. There was no difference in tissue levels, capsular thickness, or staining for Ki67 or FAPα between dogs treated with 0.5% or 1% pirfenidone. CONCLUSIONS: Pirfenidone may decrease fibrosis following glaucoma shunt surgery and can potentially be used indefinitely due to minimal side effects.

Characterizing the tumor response to treatment with combretastatin A4 phosphate.

PURPOSE: To examine the pathophysiologic impact of treatment with combretastatin A4 phosphate (CA4P) in regions of tumors that ultimately either necrose or survive treatment with this agent. METHODS AND MATERIALS: Proliferation, perfusion, vessel density, and expression of vascular endothelial growth factor (VEGF) were analyzed in the KHT tumor model after treatment with CA4P. Analyses were conducted in the whole tumor and the tumor periphery. RESULTS: Perfusion in the tumor periphery decreased 4 h after treatment, but returned to baseline 20 h later. Whole-tumor perfusion also decreased 4 h after treatment, but did not return to baseline. Vessel density decreased in the tumor as a whole, but not in the tumor periphery. No significant effect on the expression of VEGF was observed, but a decrease in proliferation in the whole tumor and the periphery was noted. CONCLUSIONS: The present study shows that those areas of a tumor that survive treatment with CA4P are affected by CA4P exposure, though only transiently. The decrease in perfusion could negatively affect therapies utilizing the combination of CA4P and conventional anticancer agents by decreasing drug delivery and tissue oxygenation. These findings suggest that the timing of CA4P treatments when used in conjunction with conventional anticancer therapies should be considered carefully.

Monitoring the treatment efficacy of the vascular disrupting agent CA4P.

The purpose of this study was to investigate two non-invasive methods for determining the treatment efficacy of the vascular disrupting agent (VDA) CA4P: gadolinium enhanced dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) for perfusion analysis and enzyme-linked immunosorbent assay (ELISA) of blood samples. Candidate proteins were identified by multi-analyte profile analysis of plasma from KHT sarcoma-bearing C3H/HeJ mice after CA4P administration. Candidate proteins were further analysed by ELISA of plasma from treated C3H/HeJ, BALBc and C57BL6 mice. Changes in selected proteins, tumour perfusion and tumour necrotic fraction after CA4P treatment were then compared in individual animals. The cytokines KC and MCP-1 were observed to increase after CA4P treatment in all tested models. No correlation was found between KC or MCP-1 levels and tumour necrosis. However, tumour perfusion correlated (r=0.89, p<0.00001) with CA4P treatment efficacy as measured by necrotic fraction, suggesting that DCE-MRI may have utility in a clinical setting.